Catalysis 2026 Issue

HDS product

After MagAFS lter

Figure 7 Solid particle size distribution in coal tar liquid from MagAFS filter and HDS reactor product

In Figure 7 , a comparison is made between the PSD curves of the filter outlet stream (feed to the HDS reactor) and the HDS reactor product liquid. The former curve in the range of 6.6-22.5 nm matched very closely with the entire latter curve (4.4-29.5 nm). This finding is significant, since it appears that essentially all small particles (<30 nm) pass through the reactor freely without causing plugging problems. Particles with sizes from 260 to 1,000 nm (mostly around 400 nm) in the outlet stream from the filter may cause HDS catalyst pore plugging. However, the quantity of particles in this size range was so small that they did not cause excess pressure drop problems in the reactor during more than three years of operation, as previously shown in Figure 5. Minimising heat exchanger fouling with MagAFS filter Fouling of the heat exchanger has caused unexpected pressure drops and unscheduled shutdowns at the CSCC

HDS unit. As previously shown in Figure 5, before instal- lation of the MagAFS filter on October 1, 2020, the heat exchanger E4101G operated erratically, with pressure drops and needed quite a few unscheduled shutdowns for cleaning. Since installing the filter, no further increase (or variation) in pressure drop caused by plugging has occurred to date. Figure 8 shows the photos of the entrance plate of both heat exchangers in two parallel trains (Train 1-E4101F and Train 2-E4101L) before the HDS reactor. On the left-hand side of the photo, the plates on both trains were fouled badly before the filters were installed. With the protection of the filter, both plates on the right-hand side were shown very clean during the annual scheduled shutdown in 2023. Conclusion The MagAFS filter has been implemented commercially to clean up a more difficult feed stream (coal tar naphtha) for

Before 01/01/2021 annual shutdown (MagAFS was just installed 2 months)

Before 01/01/2023 annual shutdown

TRAIN 1-E4101F

TRAIN 2-E4101L

Figure 8 After installation of MagAFS filter in October 2020

Catalysis 2026